=== modified file 'account/account_move_line.py'
--- account/account_move_line.py	2010-09-27 11:11:55 +0000
+++ account/account_move_line.py	2010-09-29 19:22:53 +0000
@@ -1103,6 +1103,9 @@
         return True
 
     def create(self, cr, uid, vals, context=None, check=True):
+        company_id = self.pool.get('account.move').read(cr, uid, vals['move_id'], ['company_id']).get('company_id', False)
+        if company_id:
+            vals['company_id'] = company_id[0]
         account_obj = self.pool.get('account.account')
         tax_obj=self.pool.get('account.tax')
         if context is None: